Is a = b ? (1) x = y (2) c = x

Question

https://gmatclub.com/forum/download/file.php?id=63714 Is a = b ? (1) x = y (2) c = x 2021-09-15_15-31-47.png

gloriasc · Answer

Where is b ? I can’t find it in the graph!

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Bunuel · Answer

d there in the image should have been b.

PyjamaScientist · Answer

Only 2 is sufficient.

If x = c, it means that the angles are 90 ^{\circ}

From statement 1 though, we can ascertain x = y = 90 ^{\circ} 
But we can not say anything of the bottom line and angles c and b associated with it. Hence, insufficent.

So, option B is correct according to me.

100mitra · Answer

Correct Option D 
Both statement are sufficient to answer the problem

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PyjamaScientist · Answer

It is not given that both the lines are parallel. It seems you just assumed them to be true without that information being explicitly mentioned in the question.

KEADM · Answer

If x = c, how can we conclude that all angles are 90? Its not given that two lines are parallel..
Can someone please explain?

ostrick5465 · Answer

if 2 lines are parallel => a =b

(1) x = y
=> 2 horizontal lines are not sure parallel or not
=> Insuff

(2) c = x
=> 2 horizontal lines are not sure parallel or not
=> Insuff

(1) & (2) => the vertical line perpendicular to the 2 horizontal lines
=> a = b = 90 degrees
=> Suff

=> Choice C

Is a = b ? (1) x = y (2) c = x

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